A former top official in the Justice Department is daring President Donald Trump to testify during the upcoming Senate impeachment proceedings.

Neal Katyal , who was acting solicitor general under former President Barack Obama and author of the book Impeach: The Case Against Donald Trump, said on Twitter that if Trump were innocent, he should be clamoring for a chance to clear his name.

The fact that you dont speaks volumes, he wrote.

Katyal was replying to a tweet in which Trump slammed the proceedings as a no evidence, no crime, read the transcripts, no pressure Impeachment Hoax and called for an outright dismissal instead of a trial.

Katyal said thats not the behavior of an innocent person and that if Trump really believed he was innocent, he should testify to clear his name under oath before the Senate and not via Twitter. Katyal added a hashtag hes used before for Trump: #SayItUnderOath :

On Sunday, House Speaker Nancy Pelosi said dismissing impeachment as Trump and some Republicans are hoping for would amount to a cover-up.

The senators who are thinking now about voting for witnesses or not, they will have to be accountable for not having a fair trial , Pelosi warned on This Week.

She is expected to send the articles of impeachment to the Senate this week.